An alternative form of power supply is the `switch mode` system which employs a fixed frequency oscillator control running at several KHz, and controlled by varying the mark: space ratio of this frequency.
With such known arrangements the operating efficiency is not very high and may be subject to substantial heat generation and subsequent dissipation problems.
The present invention is directed to improving on such known power supplies.
According to the invention there is provided a power supply system including:
first and second series connected switching means, connected to receive a d.c. voltage; PA1 transformer means having a first winding connected to the switching means and having a second winding configured to provide a power supply output at a desired voltage; PA1 first rectification means for converting this voltage into a substantially d.c. voltage; regulation means for controlling the output within desired limits; and
optical-feedback means for providing a control path from said regulation means to said switching means to modify the switching frequency of the switching means to compensate for detected output errors.